"Specifications for 8 mm Video Cassette" dated March 1983 have been distributed by Electronic Industries Association of Japan. Like previous video cassettes, the specifications call for magnetic recording tape extending along the open front of the cassette when not in use. That extent of tape is enclosed during storage between a main visor-type lid and a smaller auxiliary lid which are automatically unlocked and retracted when the cassette is positioned on a tape deck.
U.S. Pat. No. 4,418,373 (Fujimori et al.) shows a video cassette which should substantially meet those March 1983 specifications. Fujimori FIGS. 3-6 show a pair of coil springs 19 which bias the main lid or front cover 14 toward the closed position and also indirectly the auxiliary lid or inner cover 34.
United Kingdom Patent Application No. 2,102,386A, published Feb. 2, 1983, shows a precursor of the 8 mm video cassette. FIG. 7 shows a main visor-type lid 20 which partially surrounds a tape 9 and a smaller auxiliary lid 37 which completes the enclosure during storage. Partial and complete retraction are shown in FIGS. 8 and 9, respectively. In the March 1983 specifications, the main lid covers only the outer face of the tape, and the auxiliary lid covers the entire inner face of the tape, as shown in the Fujimori patent.
The cassette of the Fujimori patent may be difficult to assemble because of the manner of securing the ends 19b of the coil springs 19. It is believed that this difficulty has been addressed by a cassette designed by Fuji Photo Film Co. to meet the March 1983 specifications. The spring mechanism of that Fuji cassette is shown in FIGS. 1 and 2 of the drawing of the present application. Referring thereto, the main visor-type lid 10 has a corner part 12 from which projects a pin 14 that is journalled in an opening in an offset 16 of a sidewall 18 of the cover or upper shell 20 of the Fuji cassette. Fitting around the pin 14 is a coil spring 22, one end of which fits into an undercut in an L-shaped projection 23 from the corner part 12 as seen in FIG. 2 which shows the inner face of the corner part 12 prior to sub-assembly of the lid 10 and the cover shell 20. The free end of the spring 22 is temporarily retained under tension by an undercut in a protrusion 25 from the corner part 12, which protrusion also serves as a latch for the lid. During assembly of the lid and cover shell, the free end of the spring 22 is moved out of the undercut in the protrusion 25 and permanently attached to the cover 20 by deforming a projection 26 over the end of the spring. While this spring mechanism should be easy to assemble, it involves some hazards. The magnetizable face of a magnetic recording tape travelling along the path 28 might touch the spring and thus be scratched, especially if there is a burr at the end of the spring. If the spring contains any magnetism, it might partially erase the tape. Deformation of the projection 26 might produce a plastic burr which could scratch the tape.